The proposed studies will examine the specific mechanisms of action of selected groundwater contaminates (benzene, trichloroethene, 1,1,1- trichloroethane, methylene chloride, carbon tetrachloride, and toluene) on the basic mechanisms of action relative to the reproductive process. These studies will build on an existing research program and will utilize in vitro methods of cell and tissue culture and employ the in vitro fertilization process. Since some of the in vitro methods proposed are applied for the first time in toxicity studies, additionally in vivo assay methods will be conducted to verify the in vitro findings. Several of these proposed test chemicals have been implicated in the reproductive dysfunction in occupationally exposed workers, yet little is known about the etiology. Some known interactions between these chemicals and the cellular functions in other organs suggest that they may interrupt the processes of reproduction by altering the permeability of cellular membrane, depression of calcium pump, or inhibit glycolysis and cell proliferation. It has also been hypothesized that these chemicals selectively inhibit the proliferation of cells at certain stages of development, while allow the growth of less differentiated ones. The in vitro methods developed or modified in our laboratories will be used to study the processes of sperm capacitation, the acrosome reaction, sperm and egg fusion, and embryonic development, which normal function require scheduled biochemical and structural changes of cellular membranes. Studies will also be conducted to compare the cytoxicity of these chemicals in embryonic cells before and after the initiation of differentiation, i.e. before and after the compaction. These results will not only aid in determining the exact effects of the chemicals on gametes and embryonic cells, they will also have important implications relative to the chemicals' ability in interrupting intercellular communication signals in other tissues.